1. Field of the Invention
The present invention relates to a method for disposing synthetic resinous material and an apparatus therefor, in the case of use of synthetic resinous material such as plastic as a fuel for a furnace and as a reducing agent for an iron source.
2. Description of the Related Arts
Recently, industrial waste and nonindustrial waste comprising synthetic resinous materials such as plastic are steeply increasing, and their disposal is a big social problem. In particular, since plastic, i.e., polymeric hydrocarbon compounds, have high combustion calorific power and damage furnace walls during disposal by combustion in general combustion furnaces, large amounts of plastic are dumped into landfills and the like without disposal by combustion. Dumping of plastic and the like is, however, undesirable in view of environmental disruption, and lack of landfill sites nowadays is a social problem. Therefore, methods of mass-disposal other than dumping are eagerly awaited for these synthetic resinous materials.
Under such circumstances, methods for using synthetic resinous materials such as plastic as an auxiliary fuel or a reducing agent for an iron source are disclosed in Japanese Patent Laid-Open No. 8-507105 and Japanese Patent Publication No. 51-33493. These methods include blowing of pulverized synthetic resins into a blast furnace thorough a tuyere. The former, for example, discloses a particle size of 1 to 10 mm and a bulk density of 0.35 or more as actual conditions.
It is, however, said that synthetic resinous wastes contain approximately 15% on average of chlorine containing polymeric resins such as vinyl chloride resins. When supplying such synthetic resins into a blast furnace and the like, a large amount of toxic gas, e.g. hydrogen chloride, forms due to thermal decomposition or combustion of the chlorine containing polymeric resins and causes severe environmental pollution. Since the toxic gas is also a highly corrosive gas, it causes corrosion in pipework. Thus, only chlorine containing polymeric resins must be selectively removed in advance from the synthetic resinous material with high efficiency in order to prevent occurrence of such harmful gas.
Synthetic resinous material contained in industrial waste and non-industrial waste consists of various types, forms and shapes. For example, there are several hundred types of synthetic resinous materials, e.g., thermoplastic resins such as polyethylene and polyvinyl chloride, thermosetting resins such as phenol resins, engineering plastic and the like. These are present in the form of blocks such as plates, film or composite materials. Further, the material is present in various shapes, such as particles, long-size products and large-size products.
For removing in advance only the chlorine containing polymeric resins from waste synthetic resinous material, a wet separating process and a centrifugal separating process using gravity differences have been proposed. However, these separating processes have the following problems because the waste synthetic resinous material consists of various types, forms and types as described above.
(1) The resinous material must be made a uniform size in order to prevent shelf hanging and the like in separating equipment. Therefore, prior crushing for making resinous materials having different forms and shapes a uniform size is required.
(2) Wet separation processes are not capable of separating chlorine containing polymeric resins from other resinous materials when both have similar specific gravities.
(3) Separation efficiency may be low in some types of waste synthetic resinous material, for example, glossary wrapping film.
(4) Chlorine containing polymeric resins cannot be separated from composite materials, such as laminated sheets, comprising the chlorine containing polymeric resins and other resin(s).
(5) Since a separation liquid is used in the wet separation system and the centrifugal separation system using specific gravity differences, the process cost increases for disposing of the used, contaminated separation liquid.
(6) The separated chlorine containing polymeric resins must be disposed by a different process.
As described above, previous removal of chlorine containing polymeric resins from waste synthetic resinous material using a wet separation process and a centrifugal separation process using specific gravity differences has various problems for practical use. Therefore, simplified and economical disposal of chlorine containing polymeric resins contained in the waste synthetic resinous material is an important factor which determines the success of mass-disposal of synthetic resinous material as a fuel and the like.